* [PATCH v2 1/1] mm: move bad zone checking in gfp_zone()
2024-09-05 10:22 ` David Hildenbrand
@ 2024-09-05 10:48 ` Wang Yibo
2024-09-05 13:13 ` David Hildenbrand
2024-09-06 3:35 ` [PATCH] mm: move bad zone checking before getting it Lucien Wang
2024-09-06 3:50 ` Lucien Wang
2 siblings, 1 reply; 6+ messages in thread
From: Wang Yibo @ 2024-09-05 10:48 UTC (permalink / raw)
To: david; +Cc: akpm, lcnwed, linux-kernel, linux-mm, trivial, wangyibo
When flags in gfp_zone() has an error combination,
VM_BUG_ON() should first know it before use it.
Signed-off-by: Wang Yibo <wangyibo@uniontech.com>
---
include/linux/gfp.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index f53f76e0b17e..ca61b2440ab3 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags)
{
enum zone_type z;
int bit = (__force int) (flags & GFP_ZONEMASK);
+ VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
((1 << GFP_ZONES_SHIFT) - 1);
- VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
+
return z;
}
--
2.20.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2 1/1] mm: move bad zone checking in gfp_zone()
2024-09-05 10:48 ` [PATCH v2 1/1] mm: move bad zone checking in gfp_zone() Wang Yibo
@ 2024-09-05 13:13 ` David Hildenbrand
0 siblings, 0 replies; 6+ messages in thread
From: David Hildenbrand @ 2024-09-05 13:13 UTC (permalink / raw)
To: Wang Yibo; +Cc: akpm, linux-kernel, linux-mm, trivial, wangyibo
On 05.09.24 12:48, Wang Yibo wrote:
> When flags in gfp_zone() has an error combination,
> VM_BUG_ON() should first know it before use it.
>
> Signed-off-by: Wang Yibo <wangyibo@uniontech.com>
> ---
> include/linux/gfp.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index f53f76e0b17e..ca61b2440ab3 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags)
> {
> enum zone_type z;
> int bit = (__force int) (flags & GFP_ZONEMASK);
> + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
>
> z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
> ((1 << GFP_ZONES_SHIFT) - 1);
> - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
> +
I'm afraid you either missed half my review comments or your answer to
my mail did not make it to my inbox.
--
Cheers,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm: move bad zone checking before getting it
2024-09-05 10:22 ` David Hildenbrand
2024-09-05 10:48 ` [PATCH v2 1/1] mm: move bad zone checking in gfp_zone() Wang Yibo
@ 2024-09-06 3:35 ` Lucien Wang
2024-09-06 3:50 ` Lucien Wang
2 siblings, 0 replies; 6+ messages in thread
From: Lucien Wang @ 2024-09-06 3:35 UTC (permalink / raw)
To: David Hildenbrand; +Cc: akpm, linux-mm, linux-kernel, trivial, Wang Yibo
On Thu, Sep 5, 2024 at 6:22 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 05.09.24 11:52, Wang Yibo wrote:
> > When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it.
>
> s/firt/first/
>
> Please break long lines. (checkpatch.pl should have warned you)
>
> >
> > Signed-off-by: Wang Yibo <wangyibo@uniontech.com>
> > ---
> > include/linux/gfp.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > index f53f76e0b17e..ca61b2440ab3 100644
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags)
> > {
> > enum zone_type z;
> > int bit = (__force int) (flags & GFP_ZONEMASK);
> > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
>
> Better use VM_WARN_ON_ONCE() instead while at it.
>
> >
> > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
> > ((1 << GFP_ZONES_SHIFT) - 1);
> > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
> > +
>
> Unrelated whitespace change.
>
> > return z;
> > }
> >
>
> But I don't see why we would want this change? It's not like the kernel
> would crash when calculating z.
>
> Or is there some change in behavior I am missing?
On Thu, Sep 5, 2024 at 9:13 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 05.09.24 12:48, Wang Yibo wrote:
> > When flags in gfp_zone() has an error combination,
> > VM_BUG_ON() should first know it before use it.
> >
> > Signed-off-by: Wang Yibo <wangyibo@uniontech.com>
> > ---
> > include/linux/gfp.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > index f53f76e0b17e..ca61b2440ab3 100644
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags)
> > {
> > enum zone_type z;
> > int bit = (__force int) (flags & GFP_ZONEMASK);
> > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
> >
> > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
> > ((1 << GFP_ZONES_SHIFT) - 1);
> > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
> > +
>
> I'm afraid you either missed half my review comments or your answer to
> my mail did not make it to my inbox.
I did not read your first email carefully,Sorry for that.
I will reply to your comments based on your last email.
>
> --
> Cheers,
>
> David / dhildenb
>
>
> --
> Cheers,
>
> David / dhildenb
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm: move bad zone checking before getting it
2024-09-05 10:22 ` David Hildenbrand
2024-09-05 10:48 ` [PATCH v2 1/1] mm: move bad zone checking in gfp_zone() Wang Yibo
2024-09-06 3:35 ` [PATCH] mm: move bad zone checking before getting it Lucien Wang
@ 2024-09-06 3:50 ` Lucien Wang
2 siblings, 0 replies; 6+ messages in thread
From: Lucien Wang @ 2024-09-06 3:50 UTC (permalink / raw)
To: David Hildenbrand; +Cc: akpm, linux-mm, linux-kernel, trivial, Wang Yibo
On Thu, Sep 5, 2024 at 6:22 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 05.09.24 11:52, Wang Yibo wrote:
> > When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it.
>
> s/firt/first/
>
> Please break long lines. (checkpatch.pl should have warned you)
I will change it.
>
> >
> > Signed-off-by: Wang Yibo <wangyibo@uniontech.com>
> > ---
> > include/linux/gfp.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > index f53f76e0b17e..ca61b2440ab3 100644
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags)
> > {
> > enum zone_type z;
> > int bit = (__force int) (flags & GFP_ZONEMASK);
> > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
>
> Better use VM_WARN_ON_ONCE() instead while at it.
Although I do not know what results BAD ZONE flags combinations will
cause, I think maybe a BUG is necessary for security ?
>
> >
> > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
> > ((1 << GFP_ZONES_SHIFT) - 1);
> > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
> > +
>
> Unrelated whitespace change.
I will change it.
>
> > return z;
> > }
> >
>
> But I don't see why we would want this change? It's not like the kernel
> would crash when calculating z.
>
> Or is there some change in behavior I am missing?
I just think flags checking should precede using it logically, when I
review these partial codes. So I submit this patch, there is no other
reason.
>
> --
> Cheers,
>
> David / dhildenb
>
^ permalink raw reply [flat|nested] 6+ messages in thread